Shutter Speed is the length of time the camera's sensor is exposed to light. It is measured in seconds, or rather fractions of a second most of the time.
Shutter Speeds are typically written as 1/50, 1/100, 1/200, 1/1000. And when they get really slow, 1", 2", 3.2", 4", 10", 30". (The double quote mark obviously means seconds - like in geography.) On the camera, to save space, they may omit the "1/" part of the number, so if you see 10 or 10" they mean one-tenth of a second and ten seconds respectively.
Now is a good time to pick up your camera and experiment. Set the mode dial to Tv (or S). This allows you to set the Speed or (Time), while the camera calculates the Aperture automagically. What's the fastest speed your camera will do? 1/4000? What does it sound like? What's the slowest you can set? 30"? Don't bother pressing the shutter, but try 1 second and listen what it sounds like. If you have a DSLR, you might here 3 or 4 clicks. If you have a mirrorless, you might hear one or two clicks.
- Side note: A DSLR has a mirror at 45 degrees that angles light up from the lens into your viewfinder. The mirrorless cameras do away with the mirror and rely on an electronic viewfinder.
So what are all the clicks?
Click one: the mirror moves up and out of the way.
At more-or-less the same time, the shutter covering the sensor moves out of the way to expose the sensor.
When times up, the shutter closes over the sensor, ending the exposure.
And the mirror moves back down to where you can see it.
Quite fascinating when you consider the complex mechanical workings that are taking place within the fraction of a second!
We can use Shutter Speed to be creative and control the exposure. Faster speeds will freeze motion, while slower speeds will accentuate motion.
How many blurry, wobbly night-time photos have you seen on Twitbook (and taken yourself). Most cameras in Auto mode just can't cope with dark scenes and slow down the Shutter Speed to below what is practical to hold still. Generally speaking, this is probably about 1/50 of a second. (Maybe a bit slower in some circumstances.) Thus it is generally recommended to keep your Shutter Speed above 1/50 of a second, most of the time.
But you will certainly want to be creative. A slow shutter speed, controlled and deliberately set will allow you to capture interesting effects like smooth flowing water or the spinning wheels of a car. You'll need to use a tripod or some other method of stabilising the camera for best results.
Conversely, more often than not, we want to freeze the action and shoot with faster Shutter Speeds - 1/200 to 1/1000 is usually ideal. The faster the action you are photographing, the faster the shutter speed will need to be. Kids running around probably need 1/500 or more. Ball sports will likely need more than 1/1000.
Get a photo showing motion. Your subject can be anything, but obviously it should be moving. Some ideas: pets or your kids running around, cars, or pedestrians.
Suggest setting your camera to Tv or S mode, and make sure your camera is stable - perhaps place your camera on a table and use a cushion to absorb any movement. Try Speeds in the range 1/10 to 5". Experiment.